1. Field of the Invention
The present invention relates to the field of portable power cutting tools and to an apparatus which facilitates the ease and safety of handling the portable power cutting tool during the operation of the tool.
2. Description of the Prior Art
Portable power circular saws, jig saws, and other power cutting tools are widely used. Most conventional circular saws come with a flat plate attached to the bottom of the circular saw. When the circular saw is in use to cut a workpiece, the bottom plate of the circular saw comes in contact with the workpiece and slides on the workpiece as the circular saw is moving forward along the cutting direction.
The problem with the conventional flat plate device is that during the cutting operation, extra effort is required from the user of the circular saw to overcome the friction between the bottom plate attached to the circular saw and the work-piece. In addition, the standard attachment plates are heavy and have a tendency to slide in a side-to-side motion which often reduces the accuracy of the cut.
In addition, rotatory power cutting tools such as a rotary power saw can create a dangerous situation called kick-back. The heavy weight of the saw causes the saw blade to move out of the linear motion due to an unstable frictional binding of the flat attachment plate against the workpiece. As a result of this veering of the blade off a straight line motion, the blade may bind with the workpiece and subsequently kick back against the worker, thereby possibly causing serious injury to the worker.
The problem has been address by the present inventor in his U.S. Pat. No. 6,568,088 issued on May 27, 2003 for “Wheel Attachment For Portable Power Cutting Tools”. While that was a fine invention, it was learned by the present inventor that the invention as embodied in the previous patent has several drawbacks. First, the wheel attachment devices must be individually placed on the saw bracket which is time consuming and results in extra effort. In addition, the wheels are not replaceable and if one wheel is broken or is worn, it may affect the operation of the rotary power saw.
The present inventor created certain improvements in the device as disclosed and claimed in U.S. Pat. No. 6,568,088, which improvements are described and claimed in co-pending patent application Ser. No. 11/413,994 filed on Apr. 28, 2006. The present inventor has now made additional significant improvements to the device as disclosed and claimed in patent application Ser. No. 11/413,994 which substantially increases the ease of operation of the tool and provide significant advantages in the operation of the tool.
The following twenty-seven (27) patents and published patent applications are also relevant to the field of the present invention:
1. U.S. Pat. No. 1,753,959 issued to Alfred Wikstrom on Apr. 8, 1930 for “Guide Wheel For Woodworking Tools” (hereafter the “Wikstrom Patent”);
2. U.S. Pat. No. 1,808,228 issued to Eugene Hulack et al. on Jun. 2, 1931 for “Attachment For Electric Drills” (hereafter the “Hulack Patent”);
3. U.S. Pat. No. 2,676,624 issued to Arthur C. Gecmen on Apr. 27, 1954 for “Guide Carriage For Power-Driven Hand Tools” (hereafter the “Gecmen Patent”);
4. U.S. Pat. No. 2,728,141 issued to Martin Green on Dec. 27, 1955 for “Foot Plate Or Base For Cloth Cutting Machine” (hereafter the “Green Patent”);
5. U.S. Pat. No. 2,800,933 issued to Don L. Michael on Jul. 30, 1957 for “Rip Guide For Portable Electric Saws” (hereafter the “Michael Patent”);
6. U.S. Pat. No. 2,839,098 issued to Whitfield Moretti et al. on Jun. 17, 1958 for “Cut-Line Indicator For Portable Circular Saw” (hereafter the “Moretti Patent”);
7. U.S. Pat. No. 3,097,430 issued to Julius Lewinski et al. on Jul. 16, 1963 for “Cutter” (hereafter the “Lewinski Patent”);
8. U.S. Pat. No. 3,344,824 issued to Anthony Greco on Oct. 3, 1967 for “Guide Device For Portable Electric Saws” (hereafter the “Greco Patent”);
9. U.S. Pat. No. 3,839,789 issued to John E. Valkosky on Oct. 8, 1974 for “Easy Rolling Circular Saw” (hereafter the “Valkosky Patent”);
10. U.S. Pat. No. 4,087,914 issued to Arthur Edward Bates on May 9, 1978 for “Guide Assembly For Portable Saws” (hereafter the “Bates Patent”);
11. U.S. Pat. No. 4,275,501 issued to Darrell w. Haire on Jun. 30, 1981 for “Laminate Cutting Assembly” (hereafter the “Haire Patent”);
12. U.S. Pat. No. 4,414,745 issued to Gerhard Kuhlman et al. on Nov. 15, 1983 for “Guiding Arrangement For A Hand Tool” (hereafter the “Kuhlman Patent”);
13. U.S. Pat. No. 4,619,170 issued to Peter Maier et al. on Oct. 28, 1986 for “Guide For A Hand Power Tool” (hereafter the “Maier Patent”);
14. U.S. Pat. No. 4,928,662 issued to Edward Chiuminatta et al. on May 29, 1990 for “Skid Plate For Cutting Unhardened Concrete” (hereafter the “Chiuminatta Patent”);
15. U.S. Pat. No. 5,433,008 issued to David L. Barger, Jr. et al. on Jul. 18, 1995 for “Circular Saw With Variable Adjustment Stops” (hereafter the “Barger Patent”);
16. U.S. Pat. No. 5,815,931 issued to Todd Cleveland on Oct. 6, 1998 for “Cutting Guide For Controlling The Direction And Cut Of A Hand Held Power Cutting Tool” (hereafter the “Cleveland Patent”);
17. U.S. Pat. No. 5,901,450 issued to Thomas Paul James on May 11, 1999 for “Rip Guide For A Circular Saw” (hereafter the “James Patent”);
18. U.S. Pat. No. 6,202,311 issued to Richard C. Nickels, Jr. on Mar. 20, 2001 for “Circular Saw With Bevel Angle Adjustment Mechanism” (hereafter the “Nickels Patent”);
19. U.S. Pat. No. 6,397,716 issued to Andrea Garuglieri on Jun. 4, 2002 for “Bevel Saw Angle Indicator” (hereafter the “Garuglieri Patent”);
20. United States Published Patent Application No. 2002/0066190 issued to Michael Fey et al. on Jun. 6, 2002 for “Guide Means For A Circular Saw” (hereafter the “Fey Published Patent Application”):
21. United States Published Patent Application No. 2003/0070306 issued to Jon Anthony McDonald on Apr. 17, 2003 for “Apparatus For Supporting A Cutting Saw About A Substrate” (hereafter the “McDonald Published Patent Application”);
22. U.S. Pat. No. 6,568,088 issued to Mathias Am Ende on May 27, 2003 for “Wheel Attachment For Portable Power Cutting Tools” (hereafter the “Ende Patent”);
23. U.S. Pat. No. 6,757,981 issued to Philip W. Hampton on Jul. 6, 2004 for “Universal Rip Guide For Circular Saw” (hereafter the “Hampton Patent”);
24. United States Published Patent Application No. 2005/0000338 issued to Joseph Wascow on Jan. 6, 2005 for “Circular Saw Having Bevel And Depth Of Cut Detent System” (hereafter the “Wascow Published Patent Application”);
25. U.S. Pat. No. 7,159,323 issued to Alex Petrenko on Jan. 9, 2007 for “Circular Saw For Facilitating Straight Cuts And/Or Cuts At A Desired Angle Relative To A Workpiece Edge” (hereafter the “Petrenko Patent”);
26. U.S. Pat. No. 7,714,641 issued to Masaki Kondo et al. on Feb. 13, 2007 for “Cutting Tool” (hereafter the “Kondo Patent”);
27. Patent Abstract of Japan No. 2002370202 issued to Kakimoto Kazuhiro on Dec. 24, 2002 for “Circular Saw” (hereafter the “Kazuhiro Patent Abstract of Japan”).
The Wikstrom Patent discloses the concept of having a guide wheel 16 which moves ahead of the saw to assist the saw blade 18 in cutting a straight line.
The Hulack Patent discloses an attachment for electric drills including a plurality of rollers 5 which are adapted to have rolling contact with the work piece. It also shows the ability to adjust the angle of the work piece by rotatable member 35 having a channel 38.
The Gecmen Patent discloses a guide for a power driven hand tool. It discloses the concept of having the frame member C which causes the saw to move in a straight line as the guide goes against the side of the work piece as best illustrated in FIG. 1.
The Green Patent is a foot plate or base for a cloth cutting machine. It discloses the concept of having the rolling wheel assembly as best illustrated in FIG. 1. Specifically, the patent states:                “The material supporting rollers also include a central rearward material supporting roller 39, which is mounted in connection with the rear or heel end portion of the foot plate or base 10 behind the central rearward traction roller 31. In addition to said central rearward material supporting roller 39, it is preferred to also provide idler material supporting rollers 40, which are aligned with said central rearward material supporting roller 39 respectively adjacent opposite ends of the latter. A shaft 41, common to said rearward material supporting rollers 39 and 40, serves to rotatably support said rollers in such disposition that the top peripheries thereof project through an opening 14 of the foot plate or base 10, whereby to intersect the top surface of the latter, thus being operative to engage and support the material moving over said top surface during operation of the cutting machine.”        
While this patent discloses the concept of the rollers, it is placed in a different way and in a different orientation from the present invention.
The Michael Patent is a rip guide for portable electric saw and discloses the concept of having the transverse member 18 attached with a saw frame so that its vertically orientated portion 38 can be placed against the work piece to assist in guiding the saws to cut in a straight line.
The Moretti Patent discloses a guide member for guiding the straight cut of a saw. Slide 22 is provided with a rip guide being 32 mounted thereon for automatic shifting adjustment as the angle of a blade 5 is changed. Specifically,                “The beam 32 is fitted in a longitudinal channel indicated at 33 and cut in the underside of the slide 22. On its upper surface the beam is suitably marked as at 34 (FIG. 2) to indicate the correct measurements from the line indicator edge 27 to a conventional type of rip guide shoe indicated at 35 (FIG. 3). The rip guide shoe as will be readily appreciated in the art is for guiding the saw along the edge of a workpiece in making a cut.        
The beam 32 os adjustably locked on the slide 22 as by means of a clamping knob 36 in which the upper end of a clamping screw 37 extends from a recess adjacent channel 33. In the recess an eccentric foot 38 of the screw is provided to turn against the edge of the beam and releasably bind the same in the position to which it may be adjusted.”
The Lewinski Patent embodies the concept of having the rolling members contacting the plate to assist in the cutting guide feature. Specifically,                “A contact plate 20 extends under the base and has openings 21 therein in which transverse rollers 22 are rotatably mounted on axles 23 secured to the upper surface of the plate in such a manner that the rollers project through the openings in the plate and engage the material being cut. This enables the device to be moved over the material being cut easily and without any tendency for the material to move laterally as an incident thereto.”        
The Greco Patent as best illustrated in FIG. 1 once again discloses a cutting guide member with a transverse section 19 and a vertical section 22 for rolling movement to assist the saw in a cutting mode.
The Valkosky Patent discloses an easy rolling circular saw. It does disclose the concept of having rolling members in the front and back of the plate to assist in the guiding of the saw in a horizontal line. However, the overall structure of this invention is different from the present invention.
The Bates Patent is a guide assembly for portable saws. This includes:                “A guide for enabling straight-line tracking of handheld portable power saw over a work-piece having a clamp adapted to be secured at the forward edge of the sole plate of the saw, the clamp having at least one roller mounted thereon providing roller support for the saw on the work-piece, the roller having axially spaced apart work-piece engaging sections so as to inhibit angular deviation of the saw as it is moved over the work-piece.”        
The Haire Patent discloses a laminate cutting assembly. There are wheels 58 but the wheels are on swivels and therefore in addition can orient to cut the tool in various orientations because of the swivel features of the wheels.
The Kuhlman Patent discloses the concept of having a transverse guide 6 and loop shaped projection 18 which can go against the work piece to assist in guiding the cutting saw.
The Maier Patent is a guide for a hand power tool assembly and discloses a foot plate that has a recess thereon which enables it to completely straddle the guide plate while giving lateral guidance. In the recess, there are spring loaded rollers or shoes pressing on the guide plate.                “As will be seen in FIG. 3, the recess 11 is widened out in steps near the bar members 14 so that the guide plate 4 bridges over the recess 11 like a gantry or portal. In the wider part of the recess 11 there are spring loaded wheel members 19 or sliding shoes 20, that run on the topside of the guide plate 7 and give the desired loading pressure. The use of wheel members or sliding shoes means that the foot plate 4 is able to run on the guide plate 7 with little friction.”        
Therefore, this invention does disclose the concept of having the spring loaded rollers in the guide plate.
The Chiuminatta Patent is a skid plate for a concrete cutting saw which discloses the concept of rollers to assist in rolling the saw along the concrete. It also discloses:                “The pivot block 60 is spaced apart from the base plate 12 by a boss 62 so that the pivot block 60 is above the surface of the base plate 12. On the boss 62 is mounted a selector bracket 64 which comprises a piece of metal roughly resembling a sector gear in shape. The selector bracket 64 has a narrow edge extending in the direction of the extendable handle 58. Into this edge are cut recesses or notches 66. These notches 66 are shaped and located so that the can mate with a tip 68 of a plunger 70 of a solenoid 72. The solenoid 72 is mounted on, and is substantially parallel to, the extendable handle 58.”        
Therefore, this patent does disclose the concept of the orienting pivot block.
The Barger Patent discloses a circular saw which includes a means to adjust the orientation of the saw through the variable adjustment stops. Specifically, the patent states:                “In the preferred embodiment, the adjustment means includes a base member with an elongated arcuate opening. First and second stops are positioned at opposite ends of the opening. A first stop engagement member is attached to the housing of the saw and is received within the elongated arcuate opening of the base member. A second stop engagement member is selectively mounted on the first engagement member in a first position and a second position. In the first position, the first engagement member engages the first and second stops to define the limits of the planar position of the blade and in its second position, the second engagement member engages the first and second stops to define the limits of the planar positioning of the blade.”        
The Cleveland Patent discloses a cutting guide for the purpose of assisting the guiding of the saw as it cuts the workpiece. Specifically, the patent states:                “Guide arms 25 and 26 (of FIG. 1) are each formed from an elongated metal rod. Each arm 25 and 26 has a leading end portion 33, a follower portion 35, and an elbow portion 34 located between the leading end and follower portions 33 and 35. The leading end portion 33 of each guide arm 25 and 26 is sufficiently long so that the follower portion 35 can reach an edge of the workpiece. Each elbow portion 34 has a pair of bends to position the follower portion 35 about ½ inch below and in perpendicular alignment with the leading end portion 33. Thus, when the leading end portion 33 of guide arm 25 is inserted through the apertures of guide ears 27 and 29, it may be lockably positioned to allow the follower portion 35 to be selectively distanced from the saw blade 5 so as to be able to engage and ride along a side of the workpiece, thereby controlling the cutting path of the power saw 1 in a direction parallel to the side of the workpiece that is engaged by the follower portion 35 of the guide arm 25.”        
The James Patent discloses another configuration for a rip guide for a circular saw. It discloses:                “The guide member 108 also includes a second guide surface 124 spaced from and facing opposite to the first guide surface 112. The guide member 108 also includes a second rear surface 128. The second guide surface 124 and the second rear surface 128 define a second guide surface edge 132 therebetween.        When the rip guide 10 is supported by the shoe plate 40, the first and second guide surfaces 112 and 124 are generally parallel to the lateral side portions 64 and 68 of the shoe plate 40. Also, when the shoe plate 40 is orientated in the non-beveled, horizontal position perpendicular to the vertical saw blade 22, the first and second guide surfaces 112 and 124 are generally parallel to a vertical plane defined by the saw blade 22.        The guide member 108 also includes connecting member 136 between the first guide surface 112 and the second guide surface 124. As best shown in FIG. 3, the guide member 108 is substantially U-shaped. The connecting member 136 is connected at one end to the first guide surface 112 and defines a first smooth, curved or arcuate edge 140 therebetween. At the other end, the connecting member 136 is connected to a second guide surface 124 and defines a second smooth, curved or arcuate edge 144 therebetween.”        
The Nickels Patent is a circular saw with bevel angle adjustment member. The bevel angle adjustment mechanism pivotally interconnects the base to the housing such that the circular saw blade is adjustable relative to the base through a range of beveled angles. Therefore, this patent also discloses the concept of orienting the blades at different angles by the mechanism as shown in the front portion of the saw.
The Garuglieri Patent also discloses a beveled angle adjustment mechanism to adjust the angle and cut of the saw blade. It discloses:                “A bevel angle indicator for a saw is disclosed. The saw 10 consists of a table 16, a pivot support 26 pivotally mounted with respect to the table 16 about a bevel axis 92 and a mechanical saw blade pivotally mounted with respect to the pivot support 26 about a second axis 28. The pivot support 26 pivots on a pivot block 27 attached to the table 16. A gearing mechanism couples the pivot block 27 and the pivot support 26 to a dial which indicates the angle between the surface of the table 16 and the plane of the saw blade. The gearing mechanism comprises a rack 50 attached to the pivot block 27 and a pinion 54 rotatably journaled in the pivot support 26. Adjustment of the bevel angle of the saw 10 causes the pinion 54 to advance along the rack 50 and therefore rotate relative to the pivot support 26. The pinion 54 is attached to a sleeve 52, the free end of which carries a pointer 56; the pivot support 26 carries a scale 58. The pointer 56 and scale 58 indicate with accuracy the current bevel angle of the saw.”        
The Fey Published Patent Application for a guide means for a circular saw was published in 2002. It discloses a pair of wheels on the front and back of the plate to assist the saw in its movement. As set forth in Section 24, the patent states:                “The surface region 15 of the one-piece, cylindrical guide roller 12 is in contact with the surface 3 of the workpiece 4, thereby forming a contact region. The contact region extends over the entire length l of the guide roller 12. The surface region 15 has an anti-slip coating 16 made of an elastic material, such as rubber. This avoids an uncontrolled sliding of the hand-held power tool on the surface 3. The guide roller 12 extends crosswise to the working direction A over the entire width of baseplate 2.”        
The McDonald Published Patent Application again discloses the concept of having the roller assembly to assist a saw and the guide adjustment pivot mechanism 17 to adjust the angle of the saw.
The Hampton Patent is a rip guide for a circular cutting saw. It discloses a guide member which goes against the face 53 which is placed against the face of the workpiece to assist in the straight cutting of the saw.
The Wascow Published Patent Application was published in 2005 and discloses a device to assist in the angle and depth of the saw blade cut. The assembly has a bunch of notches 72 on its outer surface with a mating mechanism enabling it to lock in place through the ratchet teeth 101 as the item is adjusted by the adjusting mechanisms 96 and 99 to enable the angle of the saw to be cut at different angles.
The Petrenko Patent is a guide plate for a circular cutting saw that has a multiplicity of wheels on the bottom and in fact sites your above-discussed patent. It does disclose the concept of having straight line wheels and a multiplicity of wheels in different locations on the guide plate.
The Kondo Patent is a cutting tool which was assigned to Makita Corporation and issued in February 2007. As described in the abstract:                “The present invention provides a technique for improving the workability of a cutting tool. According to the present invention, a cutting tool may comprise a body, a base, a sub-base and a parallel ruler. The body may have a blade that can be rotationally driven. The base may be connected to the body, while the base is placed in contact with the upper surface of the workpiece. The body may tilt in a pivotal movement about an axis substantially parallel to the cutting direction such that a cutting operation can be performed with the blade projecting laterally outward from a side of the base. The sub-base may be removably attached to the base on the side from which the blade projects. The parallel ruler may be removably attached to the base on the side on which the sub-base is attached or on the opposite side of the base, together with the sub-base or in the state in which the sub-base is not attached.”        
Finally, the Japanese Published Application English abstract reads:                “A plurality of guide rollers 12a and 12b are provided to a side edge 8a along a longitudinal direction of the base 8 of the circular saw. Since the guide rollers 12a and 12b guide the floor plate by abutting against the wall when the floor plate and the like are cut with the circular saw, the wall is not stained with the impulse marks.”        
Therefore, there is a significant need for an improved device to assist in the safe operation of a rotary cutting tool and which overcomes the deficiencies in the present inventor's previous inventions.